The piezoresistive effect is a change in the electrical resistivity of a material (e.g. semiconductor, metal) when mechanical strain is applied. The electrical resistance change is due to two causes; geometry change and conductivity change of the material. The change in resistance is much more pronounced for semiconductors than for metals.
Kistler, e.g., offers only piezoresistive pressure sensors based on silicon semiconductors. For this purpose, four Si-resistors are diffused into a semiconductor membrane and connected with another to form a Wheatstone-Bridge. Under the influence of pressure, the diaphragm deforms, thereby affecting the electrical resistance of the four Si-resistors. The change in resistance is proportional to the applied pressure.
This also means that the differential voltage across the Wheatstone-Bridge is proportional to the applied pressure. The resulting differential voltage can be routed to the electrical connector for evaluation.
